Abstract

Background

Associations between soy, dairy intakes and breast cancer risk are inconsistent. No studies exist with large numbers of dairy consumers and soy consumers to assess mutual confounding.

Methods

The study cohort contains 52 795 North American women, initially free of cancer, followed for 7.9 years (29.7% were Black). Dietary intakes were estimated from food frequency questionnaires and, for 1011 calibration study subjects, from six structured 24-h dietary recalls. Incident invasive breast cancers were detected mainly by matching with cancer registries. Analyses used multivariable proportional hazards regression.

Results

The participants (mean age of 57.1 years) experienced 1057 new breast cancer cases during follow-up. No clear associations were found between soy products and breast cancer, independently of dairy. However, higher intakes of dairy calories and dairy milk were associated with hazard ratios (HRs) of 1.22 [95% confidence interval (CI): 1.05–1.40] and 1.50 (95% CI 1.22–1.84), respectively, comparing 90th to 10th percentiles of intakes. Full fat and reduced fat milks produced similar results. No important associations were noted with cheese and yogurt. Substituting median intakes of dairy milk users by those of soy milk consumers was associated with HR of 0.68 (95% CI: 0.55–0.85). Similar-sized associations were found among pre- and post-menopausal cases, with CIs also excluding the null in estrogen receptor (ER+, ER-), and progesterone receptor (PR+) cancers. Less biased calibrated measurement-error adjusted regressions demonstrated yet stronger, but less precise, HRs and CIs that still excluded the null.

Conclusions

Higher intakes of dairy milk were associated with greater risk of breast cancer, when adjusted for soy intake. Current guidelines for dairy milk consumption could be viewed with some caution.

中文翻译：

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乳制品、大豆和患乳腺癌的风险：那些混杂的牛奶

摘要

背景

大豆、乳制品摄入量和乳腺癌风险之间的关联并不一致。没有针对大量乳制品消费者和大豆消费者的研究来评估相互混淆。

方法

该研究队列包含 52 795 名北美女性，最初没有癌症，随后随访了 7.9 年（29.7% 为黑人）。膳食摄入量通过食物频率问卷估算，对于 1011 名校准研究对象，来自六次结构化的 24 小时膳食回忆。侵袭性乳腺癌主要是通过与癌症登记匹配来检测的。分析使用多变量比例风险回归。

结果

参与者（平均年龄 57.1 岁）在随访期间经历了 1057 例新的乳腺癌病例。独立于乳制品，在豆制品和乳腺癌之间没有发现明确的关联。然而，较高的乳制品卡路里和乳制品摄入量分别与 1.22 [95% 置信区间 (CI): 1.05–1.40] 和 1.50 (95% CI 1.22–1.84) 的风险比 (HRs) 相关，比较第 90 位和第 10 位摄入量的百分位数。全脂和低脂牛奶产生了相似的结果。没有发现与奶酪和酸奶有重要关联。用豆浆消费者替代牛奶使用者的平均摄入量与 0.68 的 HR 相关（95% CI：0.55-0.85）。在绝经前和绝经后病例中发现了类似大小的关联，CIs 也排除了雌激素受体（ER+，ER-）的无效，和孕激素受体 (PR+) 癌症。偏差较小的校准测量误差调整回归显示出更强但更​​不精确的 HR 和 CI，仍然排除了零值。

结论

当根据大豆摄入量进行调整时，更高的牛奶摄入量与更高的乳腺癌风险相关。可以谨慎看待当前的牛奶消费指南。